A rotary blasthole drill is drilling equipment in construction, generally used in a large-scale surface mine. When the rotary blasthole drill is working, a tower needs to be in a vertical state, and when the rotary blasthole drill is travelling, the tower should be laid down on a tower supporting frame, that is, in a horizontal state. Typically switching between the vertical state and the horizontal state of the tower is performed by a hydraulic cylinder.
In the prior art, the tower is connected to a main frame through two hydraulic cylinders, and the horizontal and vertical states of the tower are controlled by the extension and retraction of a piston rod in the hydraulic cylinder. When the piston rod of the hydraulic cylinder fully extends out, the tower is in the vertical state; when the piston rod of the hydraulic cylinder fully retracts, the tower is in the horizontal state. In particular, when oil enters into the rod-end chamber of the cylinder, the piston rod of the hydraulic cylinder begins to retract, and the tower begins to be laid down; on the contrary, when the piston rod of the hydraulic cylinder extends out, the tower begins to erect gradually.
In such a conventional manner, the speed at which the tower is laid down (horizontal state) and erects (vertical state) is controlled by adjusting the oil intake amount of the hydraulic cylinder. Since it is necessary to improve working efficiency, the tower is usually laid down at a relatively fast speed, and in this way, a large impact will act on the tower when the tower is laid down. If the oil intake amount of the oil tank is reduced, the impact on the tower can be reduced, however, this will reduce working efficiency.
In order to solve the above-mentioned problems, it is generally carried out by changing the material or reducing the oil intake amount of the hydraulic cylinder in the prior art, which results in the increase of the cost or decrease of the working efficiency of the drill.